Studies on the Clarification of Real Ale - Part Two

Abstract
Filtration of micro brewed ale is another method of affecting clarity, but at an increased capital expense. The delay in processing due to the time required for settling of olids can be offset by using filtration, but the expense and success of filtration must be taken into consideration. This study was conducted using the same micro brewed ale as in the previous study with several different commercially available filter media having different pore sizes. The clarity of the product, measured by light transmittance, and the amount of ale that could be processed prior to pore blockage were evaluated. It was found that the amount of ale that could be filtered decreased with decreasing pore size of the media, but that the clarity of the filtered ale increased somewhat. The use of several filtering aids to extend the useful life of the filter medium also was evaluated. It was found that use of filtering aids increased the cycle time of filter media significantly with little compromise in the clarity of the filtered ale. In the range of particle sizes tested, the use of the largest particles seemed to have the most beneficial effect of increasing the cycle time, while the effect of filtering aid particle size on clarity was minimal. There was some effect of filtration noted in a taste test, but that may have been due to oxygen contact during the filtration, unique to a laboratory setting, which would not be a factor in normal microbrewery operations.
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